This invention relates to high-strength, wear-resistant copper alloys and, more particularly, to high-strength, wear-resistant copper alloys having improved properties and suitable for use as a part material of a machine used under a severe sliding condition, for example, a sliding material for a sliding part, such as a rocker arm pin or a piston bush used in a valve moving mechanism of an internal combustion engine.
Conventionally, lead bronze alloys (JIS H5115) is used as a sliding material for the low or middle level load, and phosphor bronze alloys, free-cutting phosphor bronze alloys (JIS H3270), high strength brass alloys, aluminum bronze alloys, low-friction, high-strength brass alloys disclosed in the preceding applications of the present inventors (JP-B-53-44135 and JP-B-56-11735) and other alloys are known as high-load sliding materials.
However, such conventional alloys are practically unsatisfactory with respect to the wear resistance property or the anti-seizure property under a severe sliding condition, e.g., a high-speed, high-load condition, and a sliding material further improved in performance is now expected.
In recent days, needs for improvements in the engine performance, e.g., high power, high speed and high load and a reduction in fuel consumption have markedly been increased. Also, the conditions under which sliding materials for bearings and the like are used have become more severe.
Conventionally, alloys such as phosphor bronze alloys, high strength brass alloys and aluminum bronze alloys have widely been used as materials having the high wear resistance property. Phosphor bronze alloys, however, are inferior in the strength and the seizure properties under a high-speed, high-load sliding condition. Aluminum bronze alloys are generally satisfactory in strength but are inferior in the wear resistance and seizure properties. High strength brass alloys also recommended as a wear resistant material are inferior in each of the strength, the seizure property and the wear resistance properties.
As mentioned above, the conditions of use are becoming more severe and presently there is no material satisfactory in terms of the strength, the wear resistance property and so on under a high-speed, high-load condition. This is a serious problem in this technical field and there is therefore a need to develop a sliding material having the high toughness and the good wear resistance property.